Stereo imaging velocimetry
First Claim
1. A method for measuring three-dimensional velocities at a plurality of points in a fluid, comprising the steps of:
- positioning at least two cameras to view a fluid with the cameras being approximately perpendicular to one another;
defining a coordinate system for each camera based on a world coordinate system;
recording a two-dimensional view of the fluid seeded with tracer particles for each camera;
determining centroid coordinates from the two dimensional images of the tracer particles;
determining tracer particle tracks as viewed by each camera based upon the determined centroid coordinates; and
stereo matching the two dimensional tracer particle tracks between the camera views for finding three-dimensional locations of the tracer particles as a function of time and measuring velocities thereof.
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Accused Products
Abstract
A system and a method for measuring three-dimensional velocities at a plurality of points in a fluid employing at least two cameras positioned approximately perpendicular to one another. The cameras are calibrated to accurately represent image coordinates in world coordinate system. The two-dimensional views of the cameras are recorded for image processing and centroid coordinate determination. Any overlapping particle clusters are decomposed into constituent centroids. The tracer particles are tracked on a two-dimensional basis and then stereo matched to obtain three-dimensional locations of the particles as a function of time so that velocities can be measured therefrom. The stereo imaging velocimetry technique of the present invention provides a full-field, quantitative, three-dimensional map of any optically transparent fluid which is seeded with tracer particles.
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Citations
20 Claims
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1. A method for measuring three-dimensional velocities at a plurality of points in a fluid, comprising the steps of:
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positioning at least two cameras to view a fluid with the cameras being approximately perpendicular to one another; defining a coordinate system for each camera based on a world coordinate system; recording a two-dimensional view of the fluid seeded with tracer particles for each camera; determining centroid coordinates from the two dimensional images of the tracer particles; determining tracer particle tracks as viewed by each camera based upon the determined centroid coordinates; and stereo matching the two dimensional tracer particle tracks between the camera views for finding three-dimensional locations of the tracer particles as a function of time and measuring velocities thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for measuring three-dimensional velocities at a plurality of points in a fluid, comprising:
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at least two cameras positioned to view a fluid seeded with tracer particles, said at least two cameras being positioned approximately perpendicular to one another, said at least two cameras providing two-dimensional views of the tracer particles seeded in the fluid; signal processing means connected to said at least two cameras for receiving and recording the two-dimensional views; centroid determining means connected to and in communication with said signal processing means for accurately locating a centroid of each tracer particle in a frame and establishing coordinates therefor; means for decomposing overlapping tracer particle clusters into constituent centroids connected to and in communication with said signal processing means and said centroid determining means; means for tracer particle tracking of the velocity of individual tracer particle images connected to and in communication with said signal processing means, said centroid determining means, and said overlapping tracer particle decomposing means, said tracer particle tracking means determining a correspondence between individual tracer particles over time and across orthogonal views to track in two dimensions; and means for stereo matching connected to and in communication with said signal processing means, said centroid determining means, said overlapping tracer particle decomposing means and said tracer particle tracking means; said stereo matching means determining which individual tracer particle images from synchronized images represent identical tracer particles;
said stereo matching means calculating three-dimensional coordinates from the two-dimensional coordinates as a function of time and distance of the tracer particles in the fluid stream for measuring the three-dimensional velocities at the plurality of points in the fluid. - View Dependent Claims (15, 16, 17, 18)
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19. A system for collecting quantitative, three-dimensional flow data from an optically transparent fluid having tracer particles, comprising:
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at least two cameras situated approximately perpendicular to one another for viewing the fluid with tracer particles; image analysis means connected to said at least two cameras for receiving and recording two-dimensional views therefrom; and a computer connected to said image analysis means and in communication therewith, said computer first determining a centroid with coordinates for each tracer particle and then determining tracer particle tracks as viewed by each camera from the centroid coordinates, said computer generating three-dimensional locations of the tracer particles as a function of time with means for stereo matching between camera views to collect quantitative, three-dimensional flow data. - View Dependent Claims (20)
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Specification